As you might guess from the name, the technique is a bit loose and can incorporate most anything. This is my version of Robin's original vision. Actually, as I recall, it had come to her in a dream. But anyway, take a piece of cardstock, any size, any color, matte, glossy, whatever. Gather some scraps, bits of fiber, ribbon, mesh, any fun elements. Grab some stamps and inks and embossing powders, just about anything else you'd like to use. Okay, now just start either adhering elements to your cardstock, or stamp on it first. This is a very random thing. Your scraps don't have to all fit within the page. It's okay if stuff sticks out over the edges, but fill the page and have fun with it. You can trim it up later if you want to. Here's what one of mine looked like.
I used mesh, leftover scraps and diecuts, sprayed it with gold webbing. Some people like to use stamps alone and combine them in collage fashion all over the page. I like using a lot of different textures and elements. There's no right or wrong. Anything goes!
Next, cut your cardstock into 1 1/4 inch squares. You can then mount the squares on a slightly larger piece of cardstock or layer them directly onto the front of a card in different designs or patterns. Here are a couple of my examples from this sheet.
And finally, I used the last few scraps of my serendipity page for some diecuts. Here's the card with those.